Refining used lubricating oils with sulfuric acid and hydrogenation



United States Patent 2 Claims. 61. 208-179) This invention relates to a process for re-refining used engine lubricating oils or used industrial lubricating oils containing also engine-lubricating oils.

The expression used lubricating oil relates to engine and industrial lubricating oils which, due to their use, do not comply with their original composition.

It is known that the collection and re-refining of the used lubricating oils is realized throughout the World and mainly in the countries having no suitable home pctroleum basis.

The known processes serving for the re-refining (regeneration) of used lubricating oils employ a regeneration process using a treatment with sulphuric-acid and bleaching earth or with a solvent or both. The object of these processes is to extract from the used lubricating oil the changed lubricating-oil components and the impurities, and thereby to recover in pure form the unchanged part of the primary lubricant. The disadvantage of these processes is that they are not economic because they work with high losses, especially if the engine-lubricating oil component of the starting material, i.e., used lubricating oil has to be recovered in a quality corresponding to that of the primary lubricant. In such cases, the losses often attain even 60%.

The object of the invention is to eliminate the abovedescribed disadvantages and to provide a regenerating process which makes it possible to utilize the changed components, as. well as to recover in practically unchanged quantity the engine-lubricating and other lubricating components of the used lubricating oil.

With the aid of the process according to the invention it is possible to recover from used lubricating oils products of better quality than that of the primary lubricants. Accordingly, the prior art view, according to which the properties of the re-refined lubricant cannot be better than those of the primary lubricant, is not applicable to the product obtained in accordance with the present invention.

The invention resides in a process for re-refining used engine-lubricating oils or used industrial lubricating oils containing also engine-lubricating oils, comprising the steps of prepurifying the used lubricating oil with a coagulating agent and/or by vacuum distillation and subjecting' the prepurified used lubricating oil to catalytic hydrogenation under a pressure of 15 to 50, preferably 20 to 40 atm., at a temperature of 280 to 380 C., preferably 320 to 360 C., with a space velocity of 0.5 to 2.0, preferably 0.5 to 1.0 liter/liter/hour and with a gas-liquid ratio of to 120 Nm. /m. preferably 20 to 80 Nmfi/ m. in the presence of a hydrorefining catalyst and, if desired, fractionating the obtained re-refined lubricant.

As the pressure of the hydrogenation according to the invention can be varied between 20 and 40 atm., in the practice the hydrogen-rich products of the catalytic refining process can be very advantageously used under their own pressure of about 20 to 40 atm. Pure hydrogen or synthesis gas can be also advantageously employed. Used engine lubricating oils containing gas oil may also be processed according to the invention.

A great advantage of the invention consists in the fact that, as contrasted with the conventional regeneration processes consisting of several steps, it consists but of tW steps, namely, of pre-cleaning and hydrogenation. Moreover, it ensures, at considerably lower costs, a high yield,

especially of the most valuable engine lubricating oils.

Nickel oxide and molybdenum trioxide on an aluminum-oxide carrier, preferably on gamma-aluminum- -oxide, can be advantageously used as catalyst. The catalyst may contain other metal oxides, such as ferric oxide and silica as well. The nickel and molybdenum oxides can be preferably used with a NiO:MoO ratio of 4l2:620. The following composition of the catalyst has been found very advantageous:

NiO, 4-5 parts M00 15-17 parts SiO 0-5 parts, preferably 0-2 parts 'Fe O 0-15 parts, preferably 5-10 parts.

-and at least 0.1% by weight of bound sulphur, under atmospheric or higher pressures, at temperatures exceeding .200 C., for 4 to 12 hours.

(gther known activating treatments can be employed as wel The process according to the invention gives a product of suitable viscosity, viscosity index, po-ur point and flash point, colour and odour. The oxidation stability of the product is better than that of the primary lubricants obtained by conventional methods. A further advantage of the invention is that it can be employed in the existing oil-hydrogenating or desulphurizing works, Without requiring new installations. Moreover, used lubricating oils originating from mixed collection can be also employed as the basic material for the re-refining process.

The process according to the invention is further illustrated by the following examples.

EXAMPLE 1 A used lubricating oil consisting of used engine-oils and used industrial lubricating oils and containing 7% by weight of water is treated with 5% by weight of concentrated sulphuric acid. In this Way, with a loss of 17.5% by weight, 82.5% by weight of prepurified used oil are obtained. This oil is hydrogenated at a pressure of 40 atm., a temperature of 360 C., with a space velocity of 0.5 liter/liter/hour and with a gas-liquid ratio of 0.1 Nm. liter, with a synthesis gas containing by volume of hydrogen and 25% by volume of nitrogen, using a catalyst consisting of 4.5% by weight of nickel oxide, 16% by weight of molybdenum trioxide, 2% by weight of silica and 7% by weight of iron oxide, on a carrier of gamma aluminum oxide. Before use, the catalyst was heat-treated in the hydrogenation reactor in a stream of synthesis gas at 200 C., whereafter the catalyst was sulphided under a pressure of 40 atm., at a temperature of 350 C., with a space velocity of 1.0 liter/liter/hour, with a gas-liquid ratio of 0.5 Nm. /liter, with a gas oil containing 2% by weight ofbound sulphur.

The hydrogenated product leaving the reactor is fractionated under vacuum. In this way, the following products are obtained, in percent by weight with reference to the used oil forming the starting material:

Percent by weight The same used lubricating oil is prepurified by the same method and the 82.5% by weight of prepurified used oil obtained is processed by the conventional re-refining technology, that is by distilling the prepurified used oil under vacuum, extracting the fraction containing the engine oils with furfural and treating the thus-obtained solvent raflinate as well as the distillates containing lubricating oils with sulphuric acid and bleaching earth. In this way the following products are obtained:

Percent by weight Gas oil and industrial use oils 38.9 Re-reiined engine oil 26.4 Heating oil 8.5 Prepurification losses 17.5 Regeneration losses 8.7

Total 100.0

The thus-obtained re-refined engine oil has the following properties:

Viscosity index 79 Conradson residue, percent by weight 0.15 Viscosity at 50 C., cst. 59.8 Viscosity ratio V V 1.5 Conradson diflerence (C -C 1.4

By the above data it is shown that by following the process of the present invention re-refined engine oils are obtained in a considerably higher yield and better quality, and the other products of lower boiling point are of better quality too.

' EXAMPLE 2 One proceeds as described in Example 1, with the difference that the hydrogenation is carried out at 320 C., with a space velocity of 0.5 liter/liter/hour, with a gasliquid ratio of 0.05 Nmfi/liter, under a pressure of 35 atm. with reforming gas containing 90% by volume of hydrogen and by volume of light hydrocarbons. The com position of the catalyst is the same as described in Example 1 but before use, the catalyst was pretreated in the hydrogenating reactor at 210 C. with synthesis gas and then it was sulphided under a pressure of atrn. at 360 C. with synthesis gas containing 2% by weight of CS In this manner the following products are obtained:

Percent by weigh Conradson difference (C -C 1.08

4 EXAMPLE 3 One proceeds as described in Example 1 but after prepurification with sulphuric acid, the prepurified used oil is subjected to distillation under vacuum and thereby the components boiling under 420 C. are distilled off and the distillation residue containing the used engine oil is processed as in Example 1. In this way the following products are obtained:

Percent by weight Re-refined engine oil 58.2 Gas oil and industrial lubricating oil distillates 22.8 Prepurification losses 17.5 Hydrogenation and distillation losses 1.5

Total 100.0

Properties of the re-refined engine oil obtained:

Viscosity index Conradson residue, percent by weight 0.15

Viscosity at 50 C., cst 53.66 Viscosity ratio (V /V 1.54 Conradson diflference (C -C 0.86

EXAMPLE 4 One proceeds as described in Example 3, with the difference that the distillation residue is hydrogenated at a temperature of 355 C., with a space velocity of 0.25 liter/ liter/ hour, with a gas-liquid ratio of 0.12 Nm. liter, under a pressure of 20 atm. with synthesis gas containing 75% by volume of hydrogen and 25% by volume of nitrogen. In this Way the following products are obtained:

Percent by weight Re-refined engine oil 57.8 Gas oil and industrial lubricating oil distillates 22.8 Prepurification losses 17.5 Hydrogenation and distillation losses 1.9

Total 100.0

Properties of the thus-obtained re-refined engine oil:

Viscosity index Conradson residue, percent by weight 0.18

Viscosity at 50 C., cst. 46.24 Viscosity ratio (V /V 1.69 Conradson diiference (C -C 1.08

EXAMPLE 5 One proceeds as described in Example 1, with the difference that the hydrogenation is carried out at 350 C. with a space velocity of 0.8 liter/liter/hour, with a gasliquid ratio of 0.1 Nmfi/ liter, under a pressure of 50 am. with synthesis gas containing 75 by volume of hydrogen and 25% by volume of nitrogen.

In this way the following products are obtained:

Percent by weight Re-refined engine oil 53.6

Re-refined gas oil and industrial lubricating oil distillates 26.8 Prepurification losses 17.5 Hydrogenation and distillation losses 2.1

Total 100.0

The thus-obtained re-refined engine oil has the following properties:

Viscosity index 81 Conradson residue, percent by weight 0.10 Viscosity'at 50 C., cst 68.31 Viscosity ratio (V /V 1.28 Conradson difference (C -C 1.06

What we claim is: 1. A process for re-refining used engine lubricating oils and used industrial lubricating oils containing such engine lubricating oils, said process comprising the step of prepurifying the used lubricating oil by treatment with sulphuric acid; then subjecting the oil to catalytic hydrogenation at a pressure between 20 and 40 atmospheres, at a temperature between 280 and 380 C., at a space Velocity of 0.5 to 2.0 liters per liter-hour and at a gas-to-liquid ratio of 10 to 120 Nmfi/m. in the presence of a preactivated, sulphided hydro-refining catalyst.

2. The process of claim 1, wherein the hydro-refining catalyst consists of 4 to 5% by weight of NiO, 15 to 17% by Weight of M00 0 to 5% by Weight of Si0 and 0 to 15% by Weight of Fe O the said catalyst being deposited on an alumina carrier and being activated, before use, at

a temperature exceeding 200 C., in a hydrogen stream containing at least 0.1% by weight of bound sulphur.

References Cited UNITED STATES PATENTS 1,927,853 9/ 1933 Stratford 208-187 2,998,377 8/1961 Beuther et al 208-264 FOREIGN PATENTS 10 1,182,377 9/1964 Germany.

DELBERT E. GANTZ, Primary Examiner. HERBERT LEVINE, Examiner. 

1. A PROCESS FOR RE-REFINING USED ENGINE LUBRICATING OILS AND USED INDUSTRIAL LUBRICATING OILS CONTAINING SUCH ENGINE LUBRICATING OILS, SAID PROCESS COMPRISING THE STEP OF PREPURIFYING THE USED LUBRICATING OIL BY TREATMENT WITH SULPHURIC ACID; THEN SUBJECTING THE OIL TO CATALYTIC HYDROGENATION AT A PRESSURE BETWEEN 20 AND 40 ATMOSPHERES, AT A TEMPERATURE BETWEEN 280 AND 380*C., AT A SPACE VELOCITY OF 0.5 TO 2.0 LITERS PER LITER-HOUR AND AT A GAS-TO-LIQUID RATIO OF 10 TO 120 NM.3/M.3 IN THE PRESENCE OF A PREACTIVATED, SULPHIDED HYDRO-REFINING CATALYST. 